The Ultimate Guide to APIs

Application Programming Interface Deep Dive into Use Cases, Types, Benefits, and Development Tools.
Anthony Molzahn

Application Programming Interfaces (APIs) make the technology world go ‘round. We rely on APIs to get the job done, whether on your phone, computer, website, or even game consoles. They’re an integral part of application development.

These interfaces power the modern technical world as we know it. But how do they work, and why have they become so important? Let’s dive into the why’s and how’s of APIs, and the standard API tools in the market today and emerging technologies.

The Importance of APIs

While the concept of an API stems back to punchcards back in the ‘40s, the modern interpretation of the application programming interface came about in the 90s with the dawn of the web and the need for developers to access processes remotely. It was further improved upon with the introduction of the REST API, which is now the most common type of API. According to Postman’s State of API 2021, 94% of developers use REST APIs, but GraphQL is quickly growing to a wider adoption, currently floating around 34% usage among developers.

API Benefits & Use cases

It’s no surprise that APIs have a wide variety of uses. They’ve become so vital to application development and the tech world as a whole that it's hard to list all of the things that they can do. However, there are some key benefits and uses that are common across the globe, such as:

  1. Improved Collaboration. Allow your team and other developers to use your application and integrate it into theirs. APIs allow easy transfers of data between endpoints to communicate with one another, making collaborative efforts much more manageable. Internally, APIs will give your team access to the functions and data they need, improving development speed.
  2. Security. Proper API setups can be complex for malicious attackers to get into, meaning your data is safe and secure. APIs only require specific data to accept and only return what you need. That means you can process sensitive information like payment or customer data without needing to expose more than what’s necessary.
  3. Simple and Speedy. With modern APIs, data transfer is almost instant. This means your customers can access what they need lightning-quick without any lengthy delays. With proper documentation and standardization, your APIs can also be simple. Developers won’t need to stress about trying to craft complex requests, giving them more time to focus on the important stuff.
  4. Data monetization. You’ve got data, and you might be able to profit from it. Creating a paid API for your audience can unlock a new revenue source for your company. You can create custom-paid API keys to limit some or all of your API to your users, restricting what data-free users have access to or none at all.
  5. Easier innovation. APIs allow you to make your data available to whomever you choose, so you can get it into the hands of thore who need it. Want to spark a community of developers around your data? Or give your team all the access they need to get their jobs done effectively? The power of an API can spark innovation, inside or outside your organization.

How do APIs work?

In simpler terms, imagine an API being an order form for a pizza.

The order form is clearly defined, with what information they need from you. Once you fill out that form, you get a pizza back (but much quicker than 30 minutes). Further more, REST APIs are great if you offer no customizations to the kinds of pizzas offered on the menu. GraphQL APIs offer complete and precise flexibility on pizza order requests and delivery method.

Developers implement APIs in their software to allow it to communicate with other applications and send information back and forth through their system. With these API endpoints, developers can execute functions remotely or connect several different services (also known as microservices).

There are three common types of APIs, each one with different levels of access to them:

Private APIs are precisely what they sound like — private. These are typically for internal use or might have exclusive access through paid API keys. Think of how your internal system at your job works. Few people would have access to Microsoft’s internal APIs.

Partner APIs tend to be similar to their namesake. Limited access to the API, usually exclusively to other companies or software under specific circumstances. Imagine how Uber and Lyft both use Google Maps for route tracking or how websites allow you to share logins through social media accounts.

Public, as you can imagine, are open to the public. These may be locked behind an API key that you need to request, or they can be fully available for anyone to use. APIs like these can track financial information and give you access to a library of cat facts or even weather data.

We encounter APIs daily, regardless of whether or not you’re a developer. Here are some common examples of APIs you face everyday:

  • Single Sign On with social media accounts or Google accounts.
  • Payment services like Stripe, Online banking, or PayPal.
  • Streaming platforms like Netflix or Hulu.
  • Image hosting services like Giphy.

Differences between SOAP, REST, & GraphQL APIs

Because APIs have been around so long, there have been quite a few changes in the standard ways they’re structured. Let’s dive into the three most common API architectures:


Simple Objects Access Protocol (SOAP) originated from Microsoft, right before its biggest rival, REST. With SOAP, data is packaged in complex XML envelopes with all the information to be sent or received. It doesn’t rely on any particular platforms or languages outside of XML, making it fairly flexible. However, the biggest downside is the bulky and verbose XML required to function.


Shortly after SOAP was released to the public, Representational State Transfer (REST) came about and quickly became the de facto standard for APIs going forward. While it isn’t as strict as its predecessors, it does have six guiding principles for making a RESTful API:

  • A uniform interface to keep it simple for users.
  • Separation of concerns between the client and the server.
  • It must be stateless, with each request containing all the information needed to complete it.
  • Responses must be labeled as cache or cacheless, and the client can reuse the cacheable data if they wish.
  • They must work in a layered system, meaning that the client should be unable to determine whether or not the server or an intermediary (such as a proxy).


The newest of the bunch, GraphQL, is a query language and a runtime for your API. It was originally created to fix some of the flaws that came with REST APIs, mainly being that REST can only provide a fixed data structure. It also has a great place in the highly mobile world we live in today, as GraphQL APIs are better suited to making efficient data loading for those with mobile devices.

Instead of having multiple API endpoints for your data, GraphQL simplifies this by only having one for all requests. With GraphQL’s server-side running, you can make a query requesting all the data you need without making multiple API requests to multiple endpoints (known as over fetching).

API Development Tools

There are plenty of tools out there to build your API. Whether you’re aiming for RESTful, SOAP, or GraphQL, your team has many options. Take a look at the top most popular ones (in no particular order).

  1. Hoppscotch - A lightweight web-based API development platform designed with accessibility in mind. It’s free and open source and supports both REST and GraphQL. It’s relatively new but is quickly becoming a popular tool and offers both a web application and a PWA.
  2. Postman - One of the most popular tools out there, Postman has been a solid contender as a robust tool for testing and building APIs. It has advanced insights and a powerful central platform for collaboration, design, mocking, and creating documentation.
  3. Devii - The Instant API and Auto Resolver platform that automates GraphQL schemas. Built with developers in mind, Devii’s Instant API engine rapidly generates GraphQl endpoints for developers which removes those mundane, time-consuming back end dev tasks from their workload. Enterprise DevOps teams use Devii to rapidly move through their digital transformation plans. Smaller teams and individual engineers use Devii to auto deploy their databases and stand up APIs with a click of a button. Devii opens up more time in an engineer's schedule to work on the features of their project, not just the framework.
  4. Apollo GraphQL - Leveraging the power of GraphQL, Apollo is a client that lets you take full advantage of the query language. Their Supergraph platform allows you to take your API to the cloud, connect your individual apps, and deliver an easy-to-use API for your team.
  5. Apollo - Not to be confused with its GraphQL cousin, Apollo is a massive REST API that can provide you with all kinds of data for your business needs. Apollo has it all, whether for workflow management, record or outreach management, or just data.
  6. GraphiQL - A robust IDE for GraphQL API development. This tool is backed by the GraphQL Foundation and provides a comprehensive solution to developing within the ecosystem. It comes with all the features you expect from an IDE, with the benefits of auto-complete and query history.
  7. Hasura - Another powerful GraphQL tool, Hasura allows you to rapidly set up a scalable backend that works in real-time. It can fit into any tech stack with minimal coding and supports the most popular databases.
  8. Zapier - While not an API development tool, Zapier offers a platform that allows you to integrate your API with them to create powerful automation in your workflow. Trigger Slack alerts or emails based on business needs, and automate services in one robust tool.
  9. Prismatic.io - Similar to Zapier, Prismatic offers a platform that lets you integrate your products with a vast swath of popular tools and services. Through their library of API connectors, you can integrate with nearly any tool out there or create your integration with their SDK.
  10. Strapi - Offering a highly customizable headless CMS, Strapi offers a speedy platform to get your website up and running in no time. It allows you to create a robust API within the browser without any code needed and customize it how you choose, all within its admin panel.
  11. Stepzen - If you want to take your API to the next level, Stepzen offers GraphQL-as-a-service, meaning you can build your API quickly and with a faster deployment time. It’s built on the idea that a declarative approach to GraphQL is the quickest solution and allows your developers to automate parts of their workflow so they can focus on the big picture.

This list is just the tip of the API development tools iceberg. But many of these options still require developer time for manual API generation. Next-gen API automation tools, like Devii, are speeding up API design, development, and deployment.

Meet Devii, the Instant API Engine.

Manual API development can take a long time, but it doesn’t have to. API automation options save teams from bloating their development cycles by getting instant feedback on schema changes, faster updates to existing APIs, and cutting the burden of perfectly architecting your databases ahead of development.

Devii, the Instant API Engine, removes the need for manual API development by spinning up a reflection of any SQL database in seconds. Powered by GraphQL, Devii delivers CRUD queries and automates filtering and sorting for your queries from the get-go. Designed to help your team by fetching data on day one, Devii connects your existing database in just a few clicks, and allows you to host within Devii as well. With Devii, teams can:

🎛️ Control access without role-base security threats. Configure and manage all your APIs in one place with Policy-Based Access Control with default deny.

⏩ Autogenerate resolvers without the time waste. Devii Auto Resolvers help you deploy releases faster with instant, robust resolvers that handle the complex fetch requests with ease including filters, joins, sorting, pagination, and mutations. 

⚡ Go beyond standard triggers and add fast, powerful server-side functionality to any app with Devii Process Programs and Rules. With the press of a button, jumpstart your app development with out-of-the-box standard Packages including geospatial data storage and query, file storage and retrieval, payment processing, email and text alerts, PDF generation, and more.

APIs empower teams to automate tasks by integrating programs and databases with industry applications. They ensure a smooth and continuous communication between applications and allow developers to enjoy the benefits of multiple cloud-based apps while promoting innovation. 

Eliminate manual API development and make development time up to 50% faster per project with Devii. Book a demo today.

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